Deepu, V; Sujith, R; Mridula, S; Aanandan, C K; Vasudevan, K; Mohanan, P(Wiley InterScience, August , 2009)
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Abstract:
An asymmetric coplanar strip (ACS) fed dual band F-shaped antenna covering the 2.4/5.2 GHz WLAN bands is presented. The optimized dimensions of the proposed uniplanar antenna are 21 mm × 19 mm when printed on a substrate of dielectric constant 4.4 and height 1.6 mm. The dual band nature of the antenna is brought about by the various current paths in the F-shaped structure and the ground plane. The antenna exhibits nearly omnidirectional radiation characteristics and moderate gain in both the operating bands. Details of the antenna design, simulation, and experimental results are presented and discussed.
Bindu, G; Anil, Lonappan; Vinu, Thomas; Anandan, C K; Mathew, K T(Progress In Electromagnetics Research, 2006)
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Abstract:
Active microwave imaging is explored as an imaging
modality for early detection of breast cancer. When exposed to
microwaves, breast tumor exhibits electrical properties that are
significantly different from that of healthy breast tissues. The
two approaches of active microwave imaging — confocal microwave
technique with measured reflected signals and microwave tomographic
imaging with measured scattered signals are addressed here. Normal
and malignant breast tissue samples of same person are subjected to
study within 30 minutes of mastectomy. Corn syrup is used as coupling
medium, as its dielectric parameters show good match with that of
the normal breast tissue samples. As bandwidth of the transmitter is
an important aspect in the time domain confocal microwave imaging
approach, wideband bowtie antenna having 2:1 VSWR bandwidth
of 46% is designed for the transmission and reception of microwave
signals. Same antenna is used for microwave tomographic imaging too
at the frequency of 3000 MHz. Experimentally obtained time domain
results are substantiated by finite difference time domain (FDTD)
analysis. 2-D tomographic images are reconstructed with the collected
scattered data using distorted Born iterative method. Variations of
dielectric permittivity in breast samples are distinguishable from the
obtained permittivity profiles.
Aanandan,C K; K G Nair; Mohanan,P; Jacob,George(Department of Electronics, November , 1998)
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Abstract:
A new compact microstrip antenna element is analyzed.
The analysis can accurately predict the resonant frequency,
input impedance, and radiation patterns. The predicted results
are compared with experimental results and excellent agreement
is observed . These antenna elements are more suitable in applications
where limited antenna real estate is available
Aanandan,C K; Mohanan,P; K G Nair; Supriyo,Dey(Department of Electronics, February 3, 1994)
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Abstract:
The closed form expression for the radiated power of a half-wave
microstrip patch is modified to calculate the impedance
bandwidth of a printed dipole. Analyses of cavity backed flared
and end-loaded printed dipoles are presented
Aanandan,C K; Mohanan,P; K G Nair(Department of Electronics, October , 1992)
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Abstract:
Reduction of radar cross -section of dihedral corner reflectors using
simulated corrugated surface (SCS) is reported. The technique is
found to be more effective in the reduction of RCS or corner reflectors
for normal incidence . A typical reduction of 40-50 dB is
achieved using this method.
Aanandan,C K; Mohanan,P; K G Nair; Deepukumar,M; George,J(Department of Electronics, August 15, 1996)
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Abstract:
A new dual port microstrip antenna geometry for dual frequency
operation is presented. The structure consists of the intersection
of two circles of the same radius with their centres displaced by a
small fraction of the wavelength . This antenna provides wide
impedance bandwidth and excellent isolation between its ports.
The gain of the antenna is comparable to that of a standard
circular microstrip antenna operating at the same resonant
frequency. A theoretical analysis for calculating the resonant
frequencies of the two ports is also presented
Aanandan,C K; K G Nair; Mohanan,P(Department of Electronics, October , 1990)
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Abstract:
A microstrip antenna with large bandwidth is developed
using a parasitic technique. Compared to the available wide-band antenaas,
the proposed antenna structure Is very compact and gives a less
distorted radiation pattern with frequency . An impedance bandwidth,
eight times that of a conventional patch antenna of the same size, Is
achieved. The concept of coupled microstrip line model is extended for
theoretical interpretation of the impedance loci
Aanandan,C K; Mohanan,P; K G Nair(Department of Electronics, August 13, 1984)
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Abstract:
Design and development of a circularly polarized and matched H-plane sectorial horn antenna have been reported By
proper trimming of the flange parameters any desired polarization can be obtained from the horn
Deepti Das, Krishna; Aanandan, C K; Mohanan, P; Vasudevan, K(John Wiley & Sons, March 3, 2006)
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Abstract:
Design of a dual-port circular patch antenna with a sector-slot for dual-frequency operation is presented. The antenna resonates at two distinct frequencies with orthogonal polarizations and broad radiation characteristics. Unlike the conventional circular patch, this antenna can be microstrip-fed to operate at either of the resonances. The two polarizations can be simultaneously excited using two electromagnetically coupled ports with an isolation better than −30 dB between the ports. This antenna has the added advantage of size reduction of 44% compared to the conventional circular patch without any reduction in gain.
Laila, D; Deepu, V; Sujith, R; Aanandan, C K; Vasudevan, K; Mohanan, P(Wiley InterScience, May , 2009)
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Abstract:
An asymmetric coplanar strip-fed uniplanar antenna for wideband applications is presented. The resulting antenna offers a 2:1 VSWR bandwidth greater than 100% from 1.58 to 5.48 GHz covering the DCS/PCS/IEEE 802.11a/WiMAX bands. The antenna has an overall dimension of 44 × 35 mm2 when printed on a substrate of dielectric constant 4.4 and height 1.6 mm. The design equation is also presented in this article. The antenna exhibits good radiation characteristics and moderate gain in the entire operating band.
Gijo, Augustin; Shynu, S V; Mohanan, P; Anandan, C K; Vasudevan, K(Electronics Letters, April 27, 2006)
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Abstract:
A compact dual-band printed antenna covering the 2.4 GHz (2400-2485 MHz) and 5.2 GHz (5150-5350 MHz) WLAN bands is presented. The experimental analysis shows a 2:1 VSWR bandwidth of up to 32 and 8% for 2.4 and 5.2 GHz, respectively. The measured radiation patterns are nearly omnidirectional, with moderate gain in both the WLAN bands.
Sujith, R; Deepu, V; Laila, D; Aanandan, C K; Vasudevan, K; Mohanan, P(Wiley InterScience, April , 2009)
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Abstract:
A compact, dual band coplanar waveguide fed modified T-shaped uniplanar antenna is presented. The antenna has resonances at 1.77 and 5.54 GHz with a wide band from 1.47–1.97 GHz and from 5.13–6.48 GHz with an impedance bandwidth of 34% and 26%, respectively. Also the antenna has an average gain of 3 dBi in lower band and 3.5 dBi in higher band with an average efficiency of 90%.
Deepti Das, Krishna; Gopikrishna, M; Aanandan, C K; Mohanan, P; Vasudevan, K(PIER, 2008)
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Abstract:
Design of a compact dual frequency microstrip antenna
is presented. The structure consists of a slotted circular patch with
a dielectric superstrate. The superstrate,not only acts as a radome,
but improves the bandwidth and lowers the resonant frequency also.
The proposed design provides an overall size reduction of about 60%
compared to an unslotted patch along with good efficiency,gain
and bandwidth. The polarization planes at the two resonances are
orthogonal and can be simultaneously excited using a coaxial feed.
Parametric study of this configuration showed that the frequency ratio
of the two resonances can be varied from 1.17 to 1.7 enabling its
applications in the major wireless communication bands like AWS,
DECT,PHS,Wi.Bro, ISM,and DMB. Design equations are also
deduced for the proposed antenna and validated.
Deepti Das, Krishna; Gopikrishna, M; Anandan, C K; Mohanan, P; Vasudevan, K(Electronics Letters, August 3, 2006)
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Abstract:
Design of a dual linearly-polarised microstrip patch antenna, excited
by two orthogonal microstrip feed lines, is presented. A reduction in
patch size of 35% is obtained when compared to a square patch
operating at the same frequency. The polarisations are oriented at +45
and - 45 with an isolation of more than 36 dB between the ports.
Unlike earlier designs, the proposed structure provides better gain.
Aanandan,C K; Mohanan,P; Vasudevan,K; Shynu,S V; Gijo,Augustin(Department of Electronics, 2004)
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Abstract:
A novel design of a computer electronically reconfigurable dual frequency dual polarized single feed hexagonal slot loaded microstrip antenna in L-band is introduced in this chapter. pin diodes are used to switch the operating frequencies considerably without much affecting the radiation characteristics and gain. the antenna can work with a frequency ratio varying in the wide range from 1.2 to 1.4. the proposed design has an added advantage of size reduction up to 72.21% and 46.84% for the two resonating frequencies compared to standard rectangular patches. the design also gives considerable bandwidth of up to 2.82% and 2.42 % for the operating frequencies.
Thomas, Paulbert; Gopikrishna, M; Aanandan, C K; Mohanan, P; Vasudevan, K(Wiley InterScience, October , 2010)
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Abstract:
Design of a compact microstrip-fed ultra-wideband antenna suitable for USB dongle and other such space constraint applications is presented. The structure consists of a pentagonal monopole element and a modified ground plane that gives an impedance bandwidth from 2.8 to 12 GHz. Radiation patterns are stable and omni-directional throughout the band with an average gain of 2.84 dBi. The antenna occupies only 11 × 30 mm2 on FR4 substrate with permittivity 4.4.
Deepu, V; Rohith, K R; Manoj, J; Suma, M N; Vasudevan, K; Aanandan, C K; Mohanan, P(Electronics Letters, January 18, 2007)
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Abstract:
A compact dual-band uniplanar antenna for operation in the 2.4/5.2/5.8 GHz WLAN/HIPERLAN2 communication bands is presented. The dual-band antenna is obtained by modifying one of the lateral strips of a slot line, thereby producing two different current paths. The antenna occupies a very small area of 14.5times16.6 mm2 including the ground plane on a substrate having dielectric constant 4.4 and thickness 1.6 mm at 2.2 GHz. The antenna resonates with two bands from 2.2 to 2.52 GHz and from 5 to 10 GHz with good matching, good radiation characteristics and moderate gain
Shynu, S V; Augustin, G; Aanandan, C K; Mohanan, P; Vasudevan, K(IET, March 16, 2006)
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Abstract:
A new electronically reconfigurable dual frequency microstrip patch antenna with highly simplified varactor tuning circuitry is presented. The proposed design allows relatively independent selection of the two operating frequencies. Tuning ranges of 7.1 and 4.1% are realised for the two resonant frequencies without the use of any matching circuits.
Gopikrishna, M; Deepti Das, Krishna; Aanandan, C K; Mohanan, P; Vasudevan, K(Wiley InterScience, April , 2009)
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Abstract:
The design and performance of a stepped slot printed monopole antenna in the ultrawideband is presented in this article. Multiple resonances generated by the stepped slot geometry are matched in the ultrawideband using a modified microstrip feed. The impedance bandwidth (SWR < 2) of the antenna is from 3 to 11 GHz. Radiation patterns are stable and omnidirectional with appreciable gain throughout the band. Performance of the antenna is also analyzed in the time domain, which reveals good pulse handling capabilities. Compact geometry of the antenna allows easy commercial deployment.